1. Field of the Invention
The present invention relates to power units for moving automotive movable members with the aid of electric power, and more particularly to power units of a type which moves an automotive trunk lid between open and closed positions with the aid of electric power.
2. Description of Related Art
Hitherto, various power units for automotive trunk lids have been proposed and put into practical use. One of them is shown in Laid-open Japanese Utility Model Application (Jikkai-sho) 63-117979. The power unit of this application is applied to a trunk lid which is pivotally connected to a vehicle body to open and close a trunk room defined in a rear part of the vehicle body. The power unit generally comprises an electric motor mounted on a panel in the trunk room, an output arm driven by the motor, a hinge arm fixed to the trunk lid and a link extending between the output arm and the hinge arm. That is, upon energization of the electric motor, the torque of the motor is transmitted to the hinge arm through the output arm and the link, thereby to open or close the trunk lid.
However, the power unit of the publication fails to have a compact construction, which thus causes a considerable reduction in an effective luggage receiving capacity of the trunk room. Furthermore, if a cover member is applied to the power unit for protecting internal parts of the power unit, the size of the power unit becomes much increased. Furthermore, in the power unit of the publication, it is difficult to properly mount the power unit on a right position of the vehicle body in a short time because it tends to occur that some of the movable parts of the power unit make a free movement when an assembler is handling the power unit to mount the same to the right position.
It is therefore an object of the present invention to provide a power unit for an automotive trunk lid, which is constructed compact in size.
It is another object of the present invention to provide a power unit for an automotive trunk lid, which is equipped with a temporarily holding arrangement by which a given part (viz., output arm) can be temporarily held at a given position when the power unit is not assembled on the vehicle body.
It is still another object of the present invention to provide a power unit for an automotive trunk lid, wherein essential parts of the power unit are mounted on both side surfaces of a base plate to achieve a balanced mounting of the parts.
It is a further object of the present invention to provide a power unit for an automotive trunk lid, which has a base plate which is formed with a flange by which essential parts of the power unit are protected or suppressed from interfering with surrounding external members.
According to a first aspect of the present invention, there is provided a power unit for moving a lid between open and closed positions with the aid of electric power, which comprises a base plate having mutually opposed first and second side surfaces; first group of parts arranged on the first side surface, the first group of parts including an electric motor which outputs rotation, a speed reduction unit which reduces a speed of the rotation outputted from the motor and an electromagnetic clutch, the speed reduction unit having a gear member which is projected to the second side surface from the first side surface through an opening formed in the base plate and driven by the motor when the electromagnetic clutch assumes ON condition; and second group of parts arranged on the second side surface, the second group of parts including an intermediate gear which is rotatably connected to the base plate and meshed with the gear member, an output gear which is rotatably connected to the base plate through a shaft secured to the output gear and meshed with the intermediate gear and an output arm which is connected to the output gear to rotate therewith, the output arm being linked to the lid.
According to a second aspect of the present invention, there is provided a power unit for pivoting an automotive trunk lid between open and closed positions with the aid of electric power, which comprises a base plate having mutually opposed first and second side surfaces; first group of parts arranged on the first side surface, the first group of parts including an electric motor which outputs rotation, a speed reduction unit which reduces a speed of the rotation outputted from the motor and an electromagnetic clutch, the speed reduction unit having a gear member which is projected to the second side surface from the first side surface through an opening formed in the base plate and driven by the motor when the electromagnetic clutch assumes ON condition; second group of parts arranged on the second side surface, the second group of parts including an intermediate gear which is rotatably connected to the base plate and meshed with the gear member, an output gear which is rotatably connected to the base plate through a shaft secured to the output gear and meshed with the intermediate gear and an output arm which has one end secured to the shaft thereby to rotate together with the output gear, the output arm having the other end which is adapted to be linked to the trunk lid, the second group of parts being arranged flatly on the second side surface in a manner to constitute a layered structure; and a temporarily holding arrangement for temporarily holding the output arm at a predetermined given angular position, the temporarily holding arrangement including an engaging opening formed in the output arm; and an engaging projection formed on the base plate, wherein when the output arm is turned to the given angular position, the engaging opening catches the engaging projection thereby to achieve a soft latched engagement therebetween.